diff --git a/lib/SMTLIB2/Solver.cpp b/lib/SMTLIB2/Solver.cpp
index 195899cbc..47b2ef924 100644
--- a/lib/SMTLIB2/Solver.cpp
+++ b/lib/SMTLIB2/Solver.cpp
@@ -276,7 +276,7 @@ class ProcessSMTLIBSolver : public SMTLIBSolver {
         return EC;
       }
 
-      if ((*MB)->getBuffer().startswith("sat\n")) {
+      if ((*MB)->getBuffer().starts_with("sat\n")) {
         ::remove(OutputPath.c_str());
         Result = true;
         ++Sats;
@@ -288,7 +288,7 @@ class ProcessSMTLIBSolver : public SMTLIBSolver {
         if (!ErrStr.empty())
           return std::make_error_code(std::errc::protocol_error);
         return std::error_code();
-      } else if ((*MB)->getBuffer().startswith("unsat\n")) {
+      } else if ((*MB)->getBuffer().starts_with("unsat\n")) {
         ::remove(OutputPath.c_str());
         Result = false;
         ++Unsats;